1. Field of the invention
This invention relates to a composite beam, pillar or truss, to a connector therefor, and to a construction incorporating such beams.
The invention is particularly concerned with the construction of prefabricated large-scale temporary buildings such as exhibition halls, but also with structures which are not themselves buildings , for example the construction of lighting rigs.
A composite beam, pillar or truss will hereinafter be called a "beam" for convenience. It is desirable to be able to provide structures such as those listed in a variety of shapes and sizes by the use of modular construction for the beams and pillars so that only a small number of standard types of part are needed in stock.
2. Summary of the invention
It is an object of a first aspect of the invention to provide a new or improved composite beam (as defined).
According to this aspect of the invention, there is provided a composite beam comprising a plurality of modular units, each unit having identical corner formations, the units being disposed end to end to define the length of a beam;
a plurality of elongate stringers adapted to have a keyed engagement with said corner formations to connect the units together; and a pair of end caps adapted to be secured to the stringers at respective ends of the beam.
The units may be of polygonal outline and are preferably square.
Each unit may comprise a space-frame of pyramidal form comprising a plurality of struts, equi-spaced about an apertured core and intersecting a polygonal end frame.
Alternatively, each unit may be conical having an apertured core and a polygonal end frame.
The apertured core may have laterally facing and longitudinally facing apertures to permit passage of services into and through the beam. Where the unit is pyramidal, each structure may be of 3 winged, circular or triangular cross-section for rigidity,
Alternate units may be inverted when being disposed end to end.
The keyed engagement may be made between grooves of the stringers and projections or ribs of the units. Spacers may be provided between adjacent such projections or ribs to fill the grooves along their entire length.
The end caps may be arranged to bear on the units to exert a compressive pre-tension on the beam.
Tie rods passed through the stringers may be connected to the end caps to exert said compressive pre-tension, or alternatively threaded inserts may be used to exert pre-tension.
The stringers may be cut to length slightly shorter than the plurality of units to which they are keyed, so that attachment of the end caps may compress the units slightly in length.
Adhesive may be introduced into the grooves after final assembly to lock the beam together.
Since structures built up of beams may vary greatly in size and shape, it is desirable to have connectors for the beams which permit design versatility without the need for stocks of many different components to be kept.
It is therefore an object of a further aspect of the present invention to provide a new or improved connector of modular construction, capable of being connected at some or all of its faces to beams (as defined) of a structure.
According to the invention there is provided a connector for beams, the connector comprising a number of polygonal face members, each face member having connection means capable of connection to a respective beam, the face members being adapted to be connected together into a three-dimensional body having a plurality of corners at each of which three members meet, the connector comprising a corresponding plurality of internal corner members and a corresponding plurality of external corner members adapted to be secured respectively internally and externally of the corners to clamp three face members together at each of the corners.
Preferably, the polygonal face members are generally square and the three-dimensional body is a cube.
Each cube member may have a central aperture whereby services such as cables and pipework can be passed through the connector in any direction.
Each face member may have a screw thread adapted to mate with a thread provided on a beam.
Viewed from a further aspect, the invention provides a construction comprising a plurality of opposite beams as set out above, connected together by means of one or more connectors as set out above.
The construction may comprise a building.
The construction may include a rainwater drainage assembly for a roof, the assembly comprising beams secured together by connectors as set out above, the assembly further comprising a rainwater collector on said roof, a drain pipe extending from said collector to one of said connectors, and a vertical drain extending from said connector to discharge.